Control of x-ray generators



Oct. 9, 1951 A. R. BROWN 2,571,009

CONTROL OF X-RAY GENERATORS Filed Dec. 7, 1948 OF PATIENT 5ERIAL E .50 (Y O O a 00 l9 J SPACE FOR ADDITIONAL DATA 1 MRA. K. C JLZQ' I00 /faaflfirozwz pressed in terms Patented Oct. 9, 1951 CONTROL or .X-RAY GENERATORS AllanR. Brown, Oak Park, Illl, assignor to General ElectricCompany, a corporation of New York ' Application December, 7, 1948, Serial No..6.4,01 8 lzfllaims. (crest-7e93,)

The present invention relates in general to X-.ray;apparatus, and has more particular rei erence to.no.vel,and improved means for controlling X-ray .igenerating equipment, especially when used ,for therapy purposes.

iX-raygenerators commonly comprise an electron emitting cathode and a cooperating anode enclosed in a sealed .and evacuated envelope forming an X-ray tube, which functions as an X-ray generator as the result of impingement on theanode of electrons emitted by operation of the cathode. The cathode of the generator may comprise van electron emitting filament, adapted tofunctionas such when electrically excited; and electrons emittedby thezcathode may be impelled toward and caused toimpin e upon the anode at high velocity under the influence of the driving force-provided by application of anode potential between the anode and cathode during the operation of the device. I

The intensity of ,X-rays thus generated at and emitted by the anode is a function of anode potential, which determines the speed of impinging electrons at the instant of impact, and is also a function of the number of electrons hitting the anode per unit of time, conveniently referred to as the rate of electron impingement. This rate of impingement of electrons, in turn, is a function of the rated electron emission from the filament, the electron emission rate, in turn, be-

ing a function of cathode excitation. The intensity of .X-ray emission, thus, may be exof anode potentialand of cathode exciting current; and it is usual to prescribe a desired X-ray therapy treatment in terms of the voltage and cathode exciting current required to produce X-rays of the desired intensity for the treatment.

.ltis also common to utilize filters in applying X-rays for therapy purposes, which filters, to a greater or less degree, reduce the intensity of the X-ray beam as applied to the patient. Accordingly, it is the common practice to specify for-each treatment, the filter to be used, as well 'as the anode voltage and cathode exciting current, and the time interval during which therays are to be applied. The .X-ray apparatus may then be fitted with the desired filter, adjusted as to anode voltage and cathode exciting current, and theapparatus operated under the control of timing mechanism to accomplish the specified treatment. This, of course, places-reliance upon athe loperatorsof the equipment to see that the sameiis properly adjusted. Errors infilter selec- .:tion,:zor in the; adjustment otthe ztiming me hanism or of anode potential or cathode exciting current, may produce injurious variation in the intensity of rays applied to the patient, thus presenting an elementof danger to the patient through failure of the operatorproperly to adjust the eguipment. it is thus verydes irable to provide means ,assuring that the exact treatment, as p tesqribedibya ph i an. is pp d o patient, ,and especially that the correct filter be used since the possibility of error in the selection of ,the filter, with consequent-danger of overex u-re of the patient,re presents a real and apprecia eha a d gin im-portant object ofthe present invention is to-provide means assuring correct adjustment of X-ray apparatus to the requirements of the pati nt, without reliance upon the accuracy and prccisie -e th .q e a Another important object is to provide a master control template which may be formed to correspondwith; the treatment required for a patient, 'byf.-the- ;prescribing physician, and then used to ccnt plth e e i e t X:r ppa u as 19y 'nsertionof the template in a suitable recepiacl c rovide n the apparatus for the cas ;Another importantobject resides in controlling X-ray equipmentwith respect to the intensityof g ed x-rays by meansof selector switches adapted; to becontrolledby a template; .a further object being to provide a simple, inexpensive template ionthe foregoin purpose, which may ,be-cutl r lynched in accordance .with a desired therapyti atment, as by the prescribing physician, L d then used to selectively control sw tches j for regulating the operation of the ir a ap ar tus- An their important object is to providefor in ateznplate ior controlling theoperati on cf, 1 a e x rat n e u p e t-"i c m in on wit 9 737 53 fi t .s gi a th -cqe ll ar us-w llfu t nc qnfl les ihefi .0 ;respgndi ewi h th er-me tem a is op rl r tien d:intheappa atu f --The foregoing :and numerous other important n ct dv t s an inh rent t nc ien o th n enti wil ewm a par cub e ismereiulr n r t e imm a l q ie d scr ptio whic 'ta ic e n t with th .accqni a yine jdr win d s os r r ed e bo ime i-t nv ntio slt i r ine. 1 .1 1 6 ra in -.-E e-,llislas h mat diaeramioia X-..ray g natom-provided w th, con rol means embody n ath present invention; I

Fig. 2 is a plan view of a template adapted for use in controlling the apparatus shown in Fig. 1;

Fig. 3 is a plan view of a filter element adapted to be used with the apparatus shown in Fig. 1;

and

Fig. 4 is a wiring diagram of the apparatni f.

To illustrate the invention, the drawings show apparatus comprising an X-ray generator II of any suitable or preferred form and means for operating and controlling the generator, including the control panel I2 which may include the power supply and control equipment hereinafter more fully described.

The generator II may comprise an anode I3 and a cooperating cathode I4 enclosed in a sealed and evacuated envelope I5 to form an X-ray tube. As shown, the cathode I4 may comprise an electron emitting filament adapted to be energized from a suitable external power source by means of the filament power supply leads I6; and operating anode potential may be applied between the anode and the cathode, as by means of one of the filament leads I6 and an anode conductor I1.

The X-ray tube also may be suitably enclosed in a preferably shockproof housing I8, whence the leads I6 and the conductor I1 may extend through preferably shockproof cables I9 to the power supply and control panel I2. The X-ray tube I5 also may have a suitable X-ray transmitting window, and the housing I8 may be provided with a sleeve 20 in line with the window and through which X-rays may pass out of the housing I8 for application to a patient requiring treatment. The sleeve 20 may be provided with a filter mounting 2| adapted to receive any selected one of a number of filters 22 and to support the selected filter in the path of the X-ray beam transmitted to the patient.

Filters may be made of any suitable filter material, such as copper or aluminum, or other X-ray translucent material; and the filters may comprise plates of filter material of varying thickness, the X-ray absorbing characteristics of each filter material being a function of filter thickness. A set of filters may, for example, comprise a series of copper plates, respectively one, two, and three millimeters in thickness, and

aluminum plates, respectively of two, four, and six millimeters in thickness.

As shown more particularly in Fig. 4 of the drawings, operating power may be supplied from any suitable power source 24, such as an alternating current generator, through a control system 23, which may conveniently be mounted on the control box or panel I2. Power from the source 24 may be applied to the system 23 through a power supply line comprising conductors 25 and 25', including suitable disconnecting switch means 24'. As shown, one side 25 of the power source may be grounded and connected directly to the anode conductor I1, anode power being applied between the anode and the cathode of the generator as by means of a transformer 26 having a secondary winding 21 interconnected between the anode conductor I1 and one of the cathode leads I6. The transformer 26, as shown, has a primary winding 28, one end of which is connected with the grounded supply conductor 25, the other end of said winding 28 being connected with a resistor 29 provided with a plurality of voltage adjusting taps 29, six of which are shown. Cathode energizing power may be supplied to the filament I4 throiigh a transformer 30, having a secondary winding 3I interconnected between the conductors I6, and a primary winding 32, one end of which is connected with the grounded power supply conductor 25, the other end of said primary winding being connected with a resistor 33 provided with taps 33, of which three are shown. Obviously, any other suitable power supply means or arrangement, adjustable as by means of control taps, or otherwise, may be employed.

In the illustrated embodiment, however, adjustment of anode voltage is accomplished by means of the taps 29, while adjustment of cathode energizing current is accomplished by means of the taps 33. To this end, each of the taps 29' is electrically connected, as by means of suitable conductors 34, with a corresponding contact on a single-pole single-throw switch 35. Another contact on each of the switches 35 is connected, as by means of suitable conductors 34', with a corresponding switch 36, the switches 36 being arranged preferably in a vertical bank in a template receptacle 31, which may be and preferably is mounted on the panel I2. The switches 36 also are interconnected with the ungrounded or high side 25 of the power Supply line, either directly or through return circuit means hereinafter more fully described. The taps 33' are also each interconnected, as by means of suitable conductors 38, with a corresponding contact of a single-pole single-throw switch 39. Another contact on each of the switches 39 is connected, as by means of suitable conductors 38', with a corresponding switch 48, the several switches 48 being arranged, like the switches 36, in a bank in the receptacle 31 and being connected with the high side 25' of the supply line, either directly or through return circuit means hereinafter described. The movable contacts of the several switches 35 and 39 and a double-pole doublethrow switch 54, are ganged together in any suitable manner, whereby these switches may be controlled in unison.

The switches 35 and 48 are normally closed switches and are arranged with the blades thereof in contacting relationship in a plane comprising the medial plane of the receptacle 31, which receptacle preferably comprises an elongated, slot-like cavity adapted to receive a suitable template ll removably therein for the control of the switches 35 and 49.

The template 4| may comprise a plate of insulating material adapted to pass between the contacting blades of all of the switches 36 and 48, in order to open the same and 'hold the switches in open position so long as the template is mounted in the receptacle. As shown more particularly in Fig. 2 of the drawings, the template 4| may comprise a card of insulating material as, for example, a layer of plastic material, having a surface adapted to be printed and written upon with ink or by typewriter, or otherwise, and containing preferably in the upper portions thereof a space for the name of a patient and for a serial number for record keeping and filing purposes, and including space for additional data concerning the patient to whom the template applies. In its lower portions, the face of the template may be ruled or otherwise marked to indicate portions 42 adapted to be punched out selectively to form perforations in the template at various distances from the bottom edge of the template, the portions 42 being preferably arranged in vertical columns, and each perforation having adjacent identification indicia printed on the template. I

In the illustrated embodiment, one column of perforable portions 42 is labeled M. A. and the perforable portions thereof identified by the numerals 5, H3, and I5, the same representing milliamperes of cathode exciting current. The perforable portions of the M. A. column are formed in the card to register each with a corresponding one of the switches 43 when the card is fully inserted in the receptacle 31. Accordingly, when inserted, the card will open all of the switches 4|], except that switch which registers with a portion 42 that has been perforated or cut away.

' Another perforable column in the template may be labeled K. v. P. and the perforable portions thereof identified by the numerals 100,, I25, I50, 5,200, and 225, the same representing various anode voltages. The perforable portions of the K. v. P. column are formed in the card to register each with a corresponding one of the switches 36 when the card is fully inserted in the receptacle 31. Accordingly, when inserted, the card willopen all of the switches 35, except that switch which registers with a portion 42 that has been perforated or cut away.

The prescribing physician thus may punch out any selected one of the perforable portions 42 in the M. A. column, as well as any selected one of the portions 42 in the K. v. P. column.

Thereupon, by inserting the template in the receptacle 31, the switches 36 and 40 will be conditioned to adjust the system 23 automatically for operation of the X-ray generator to produce X-rays of an intensity corresponding with the anode voltage and current excitation for which the template has been punched, thereby eliminating operator error and assuring that the prescribed treatment is actually applied to the patient, e

v If desired, the template may include an additional perfora'ble column marked Time and comprising perforable portions each corresponding with a difierent interval of generator operation. A set of switches like the switches 36 and 40 may be disposed in the receptacle 3! in position to be controlled by the perforable Time column of the template, such switches being electrically interconnected to automatically control timer mechanism operatively associated with the system 23, so that the time element of the prescribed treatment may also be controlled.

As shown in Fig. 2, it is also possible and desirabl to provide on the template another perforable column marked Filter, as shown in the illustrated embodiment, the several perforable portions 42 of said Filter column being labeled to correspond with various filters of the sort shown in Fig. 3, to be selectively employed. As shown, the several perforable portions 42 in the Filter column of the template may be labeled l-Cu, Z-Cu, 3-Cu, 2-Al, 4-Al, and B-Al, the same indicating, respectively, copper filters of one, two, and three millimeters in thickness, and aluminum filters of two, four, and six millimeters thickness. The prescribing physician may punch out a portion 42 in the Filter column to correspond with the filter desired for use in the treatment.

The system 23 also may include a set of normally closed switches 43 disposed in the template receptacle 37, in position to be controlled by the Filter column of the template in the manner heretofore described in connection with the K. v. P. and M. A. columns and the corresponding switch sets 36 and 40. Each of the switches 43 may be connected with a corresponding switch of a switch set 44, as by means of conductors 45. Each conductor 45 may be connected to one terminal of a corresponding pilot lamp 46, the other terminal of each lamp 46 being connected to the grounded supply conductor 25, as by means of a suitable conductor 41.

.The switches comprising the set 44 may be disposed in the filter receptacle 2 l, and each filter may be provided with means for controlling the switches so that when a selected filter is mounted in operative position in the holder 2|, a corresponding one of the switches 44 only will be closed as a result of the presence of the selected filter in mounted position in the holder 2!. This may be accomplished by utilizing normally closed switches 44,, and by providing a strip of insulation along an edge of each filter, to open all except one of the normally closed switches 44 upon insertion of a filter. As shown, however, it is preferable to utilize normally open switches 44 and to provide each filter with a switch closing cam 48, in position to close only the corresponding switch 44 when a filter is in position in the receptacle 2 I. I v

If desired, the interconnected switches 43 and 44 may be connected in series with either one of the power supply conductors 25 or 25'. As shown, however, the switches 43 and 44 are interconnected with and betweenthe switches 36 and 40 and the power supply conductor 25'. In either case it will be seen that the apparatus will fail to operate unless a filter 22 positioned in l the pocket 2| corresponds with the prescribed filter as indicated by the punched out portion in the filter column of a template positioned in the receptacle 31. In this connection, the punched out portion of the template allows only one of the switches 43 to be closed, and unless the corresponding filter is in the receptacle and closing the corresponding switch of the set 44 which is connected with the closed switch of the set 43, the power supply circuit will remain open and the apparatus inoperative.

From the foregoing it will be apparent that the template 4! not only assures against operation of the apparatus except with the prescribed filter, but also will assure operation of the apparatus at prescribed anode voltage and cathode excitation through the selective control of the switches 35 and 46 by the template.

Suitable meters 49 and 59 may be provided on the panel l2 and connected in the system to indicate anode voltage and cathode excitation, respectively.

In order to assure that the apparatus may not operate with the template 4i incorrectly positioned in the receptacle 3?, a normally open switch 5! may be mounted in the bottom of the receptacle in position to be engaged and closed by the lower edge of the template 4! only when the template is in proper, fully inserted position in the receptacle. This switch 5i may be interconnected in series with the switch sets 43 and 44, and thereby preventing completion of the power supply circuit unless the template is properly positioned in the receptacle 3?.

If desired, manual control switches 52 and 53 and a selector switch 54 may be provided for allowing manual operation and control of the apparatus, the manual selector switches 52 and 53, respectively, having contacts connected with the control taps 29 and 33 and being connected in common for direct connection, selectively,

through'the switch 54 with the 'power' supply conductor The switch 54 is selectively operable either to connect the apparatus for manual operation and control, or for automatic operation under the control of the template 4!.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the form herein disclosed being a preferred embodiment for the purpose of illustrating the invention.

7 The invention is hereby claimed as follows:

1. Control apparatus for an X-ray generator comprising a template for selectively actuating a plurality of switches controllingly associated with said generator, said template comprising a plate of insulating material having a plurality of removable portions each respectively corresponding with one of said switches and adapted to be cut away selectively to condition th template for performance of its switch controlling function, said template comprising surfaces adjacent said removable portions for containing identifying indicia marked thereon.

2. Control apparatus for an X-ray generator comprising a template for selectively opening a plurality of normally closed switches controllingly associated with said generator, said template comprising a thin plate of insulating material adapted for insertion between the contacts of said switches for opening the same, said plate having a plurality of removable portions each positioned to register with a corresponding one of said switches and adapted to be cut away selectively to permit a selected switch to close through a cut-out portion of said template when the same is mounted in switch controlling position.

3. Control apparatus for an X-ray generator comprising means forming a pocket for the removable reception of a selectively perforable template, and circuit means for supplying electrical energy for the operation of the generator in producing a useful X-ray beam, including a plurality of switches disposed in spaced relation said pocket in position for selective operation in accordance with the perforated connection of a template in pocket mounted position to regulate the supply of operating energy to the generator.

4. Control apparatus as set forth in claim 3, including a normally open switch controlling the supply of operating energy to the generator and disposed in said pocket in position to be closed and held closed by the template only when the same is in mounted position in the pocket.

5. Control apparatus as set forth in claim 3, wherein said switches comprise normally closed contacts adapted to b selectively opened by insertion of a template between the contacts thereof in said pocket, except where a perforated portion of the template is in registration with the contacts of a switch, nd a normally open switch controlling the supply of operating energy to the generator and disposed in said pocket in position to be closed and held closed by the templat only when the same is in mounted position in the pocket, to selectively open the normally closed switches.

6. Control apparatus for an X-ray generator comprising means forming a pocket for the removable reception and support of a template member in mounted position in said pocket, and

power supply means for electrically energizing the generator at various energizing intensities for the production of X-rays at corresponding intensities, including a plurality of intensity control switches selectively operable to regulate the power supply means at each of said generator energizing intensities, said switches comprising normally closed contact elements mounted in position at said pocket to be selectively opened in response to insertion, between the contacts of said switches, of any selected and pocket mounted one of a number of template members sized for reception in said pocket and respectively formed with a perforation in position to register with the contacts of a selected one of said switches corresponding with one of said several energizing intensities, whereby to allow operation of the generator only at the energizing intensity corresponding with a selectively perforated template member mounted in switch operating position in said pocket.

'7. Control apparatus as set forth in claim 6, including disabling means mounted in said pocket and normally conditioned to prevent the delivery of energizing power to said generator, said disabling means being disposed in Said pocket in position to be conditioned to allow the supply of operating energy to the generator in response to the mounting of a template member in position in said pocket for the selective actuation of said intensity control switches.

8. Control apparatus as set forth in claim 6, wherein said intensity control switches are in normally closed position and adapted to be selectively opened by a pocket mounted template member, and a disabling switch controllingly connected with said power supply means and normally conditioned to prevent the supply of energizing power to said generator, said switch being disposed in said pocket in position to be conditioned to allow energizing power to be supplied to said generator only by a template in pocket mounted position.

9. Control apparatus for an X-ray generator comprising means forming a pocket for the removable reception of a template, and circuit means for supplying electrical energy for the operation of the generator in producing a useful X-ray beam, including a plurality of normally closed switches disposed in said pocket in position for selective operation by a template in pocket mounted position to open all but a selected one of said normally closed switches and thus correspondingly regulate the supply of operating energy to the generator, said switches comprising filter matching switches, means forming a filter receptacle for supporting any one of a plurality of filters in the X-ray beam of said generator, and a plurality of normally open filter operable switches in said receptacle and'each electrically connected with a corresponding one of said normally closed filter matching switches, any selected one of said filter operable switches being operable for closure thereof only in response to the mounting in said receptacle of a corresponding filter, whereby said power supply means may be conditioned for operation only in the event that a template corresponding with a receptacle mounted filter is mounted in switch operating position in said pocket.

10. Control apparatus for an X-ray generator comprising power supply means for lectrically energizing the generator for the production of a useful X-ray beam, means forming a receptacle for supporting any one of a plurality of filters in said X-ray beam, a separate normally open filter actuated switch in said receptacle for each of said filters, whereby each of said switches may be closed only in response to the presence of its corresponding filter in mounted position in said receptacle, means forming a pocket for the removable reception of a template, and a plurality of normally closed template switches each electrically connected with a corresponding filter switch, said template switches being disposed in said pocket and selectively operable by any one of a plurality of templates removably mounted in said pocket and adapted to open all of said template switches but the one corresponding with the pocket mounted template, said filter and template switches being controllingly associated with said power supply means to condition the same for the supply of energy to said generator only in the event that an interconnected pair of filter and template switches ar conditioned for operation respectively by a filter and its matching control template disposed in mounted position in said receptacle and pocket, respectively.

11. Control apparatus for an X-ray generator comprising means forming a pocket for the removable reception of a selectively perforated template, power supply circuit means for supplying electrical energy for the operation of the generator in producing a useful X-ray beam of desired intensity, including timing means operatively associated with said power supply means and conditionable to maintain the generator in operation during any selected one of a number of unlike operating intervals, and a plurality of switches, each comprising a pair of normally closed contacts, certain of said switches forming an energy control switch bank selectively conditionable to determine the operating intensity of the X-ray beam, and others of said switches comprising an interval control switch bank selectively operable to condition said timing means, said switches being disposed in said pocket in position to be, selectively opened in response to the insertion between said contacts, in pocket mounted position, of any selected one of a plurality of templates selectively perforated in registration with a selected switch of each of said banks, whereby said selected switches may remain closed at the perforations of said pocket mounted template and cause the generator to operate only during an operation interval and at an energy level as determined by a selected template in pocket mounted position.

12. Control apparatus for an X-ray generator having an anode and an electron emitting cathode, comprising means forming a pocket for the removable reception of a selectively perforated template, power supply circuit means for supplying electrical energy for the operation of the generator in producing a useful X-ray beam of desired intensity, including cathode exciting power supply means, anode-cathode power supply means, and timing means operatively associated with said power supply means and conditionable to maintain the generator in operation during any selected one of a number of unlike operating intervals, and a plurality of switches, each comprising a pair of normally closed contacts, certain of said switches forming a cathode excitation energy control switch bank, selectively conditionable to determine the intensity of cathode excitation, others of said switches comprising an anode-cathode power supply intensity control switch bank, and others of said switches comprising an interval control switch bank selectively operable to condition said timing means, said switches being disposed in said pocket in position to be selectively opened in response to the insertion between said contacts, in pocket mounted position, of any selected one of a plurality of templates selectively perforated in registration with a selected switch of each of said banks, whereby said selected switches may remain closed at the perforations of said pocket mounted template and cause the generator to operate only during an operation interval and at an energy level as determined by a selected template in pocket mounted position.

ALLAN R. BROWN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,094,103 Horsley et a1. Sept. 28, 1937 2,171,184 Timmons Aug. 29, 1939 2,458,814 Warren Jan. 11, 1949 2,469,982 Nemet et a1. May 10, 1949 FOREIGN PATENTS Number Country Date 487,665 Germany Dec. 14, 1929 436,593 Great Britain Oct. 15, 1935 105,729 Sweden June 7, 1939 

